Pulsation dampener

ABSTRACT

A pulsation dampener is presented which includes a bladder assembly having a bladder which retains its surface area and therefore its capability to dampen pulsations during pulsation dampening. The bladder is axially and longitudinally symmetrical. The bladder assembly comprises a bladder double sealed at both longitudinal ends by the combination of a bladder anchor bolt and a pressed metal end plate to prevent leakage. Pulsation causes the bladder to assume a clover leaf cross sectional configuration, thereby maintaining the bladder surface area constant regardless of pulsation. One end of the housing is machined so that that end may be pressed to gradually reduce its diameter toward the end while causing the wall thickness of those portions of diminishing diameter to remain essentially identical to the thickness of the unmachined unpressed wall portions of the housing.

United States Patent Loukonen July 8, 1975 PULSATION DAMPENER PrimaryExaminerCharles A. Ruehl [76] Inventor: Ernest W. Loukonen, 615 W. CivicAttorney Agent or F'rmBmard Brown Center Dr., Long Beach, Calif. 9270l[57] ABSTRACT [22] Filed: June 25, 1973 A pulsation dampener ispresented which includes a bladder assembly having a bladder whichretains its [21] Appl' 373lm surface area and therefore its capabilityto dampen Related US. Application Data pulsations during pulsationdampening. The bladder is [63] Continuation of Ser. No. 178,307, Sept.7, 1971 axially and longitudinally symmetrical. The bladder abandoned.assembly comprises a bladder double sealed at both longitudinal ends bythe combination of a bladder an- [52] US. Cl. 138/30 chor bolt and a prs d m al nd plate to prevent [51] Int. Cl. F16] 55/04 leakage. Pulsationcauses h la er to assume a clo- [58] Field of Search l38/30; 220/3 ver fcross Sectional configuration. r y m intaining the bladder surface areaconstant regardless of [56] References Cited pulsation. One end of thehousing is machined so that UNITED STATES PATENTS that end may bepressed to gradually reduce its diameter toward the end while causingthe wall thickness of 220,3 those portions of diminishing diameter toremain es- 2'273'l86 Fiscfier sentially identical to the thickness ofthe unmachined 2:968:31) l/l96l Ball unpressed Wall Portions of the g-3,449,860 6/l969 Franks, Jr. et al 220/51 X 7 Claims, 4 Drawing FiguresPATFF'TFIIJUL p, 975 3.8933185 OOOOOOOOO O:

INVENTOR.

ERNEST W. LOUKONEN ROBERT L. SASSO NE ATTORNEY PULSATION DAMPENER Thisis a continuation of application Ser. No. 178,307, filed Sept. 7, 1971,now abandoned.

BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION The presentinvention relates to pulsation dampeners.

2. DESCRIPTION OF THE PRIOR ART The prior art discloses a variety ofpulsation dampeners many of which utilize bladders. some of the priorart designs have relatively short bladder life, requiring relativelyfrequent replacement. Some of the prior art pulsation dampeners becauseof their shape, size, orientation or weight have less flexibility thanis desirable. Many of the prior art bladders cannot be easily assembledand dissembled. Many require a central mandrel.

Most of the above described disadvantages are overcome by pulsationdampener described in US. Pat. No. 2,968,319 by Melvin A. Ball. The Ballpulsation dampener uses a bladder inside a metal screen having holestherethrough, the two being tightly affixed to the interior of ahousing. The interior of the bladder has been filled with a gas such asnitrogen at a pressure of approximately 500 pounds per square inch. Asfluid flows in an opening in the housing under pulsations from theexternal line, the fluid passes through perforation holes of the screenand presses against the bladder. The pressure of the fluid forces thebladder inward thereby compressing gas inside the bladder anddissipating the energy and pressure resulting from the pulsations of thefluid in the external line.

While the Ball pulsation dampener contains significant improvements overthe prior art, it contains serious disadvantages as well. The bladder isnot longitudinally symmetrical. Accordingly, the two opposite ends areunable to symmetrically or identically contract when subjected topulsations from the external line. This causes a tendency for thebladder to wrinkle, thereby reducing the surface area of the bladder.Reduction of the surface area of the bladder reduces the capability ofthe pulsation dampener to dampen the pulsations. In addition, thewrinkling of the bladder during pulsations reduces the life of thebladder. The bladder design required by the Ball Patent is difficult tovisually inspect internally prior to installation thereby causing manyearly bladder failures because of undetected faults. In addition, thedesign of the Ball pulsation dampener includes structures which have agreat deal of weight thereby making the pulsation dampener excessivelyheavy and cumbersome as well as difficult to manufacture. In practice,the Ball pulsation dampeners have a tendency to leak, thereby graduallyreducing their capability to dampen pulsation.

SUMMARY OF THE INVENTION A pulsation dampener is presented. A firstexample comprises a housing having a bladder assembly disposed around anaxis attached therein. The bladder assembly comprises a generallycylindrical screen having a large quantity of small openingstherethrough and further includes a pressurized flexible longitudinallyand axially symmetrical generally cylindrical bladder therein One end ofthe housing, hereafter called the aft end includes a center guide plugwhich defines an interior surface fitting relatively tightly around theadjoining exterior surface of the bladder assembly.

The bladder assembly is placed inside the housing to assemble thepulsation dampener. The interior surface of the housing defines acircumferential groove around the interior circumference atapproximately the top of the inserted bladder assembly. A four-piecelocking ring assembly is fitted into the groove. The bladder assembly isthen coupled to the locking ring assembly by three cap screws or similarcoupling means. An allen set screw is then screwed through a threadedopening at the bottom of the housing and screwed against the aft end ofthe bladder assembly to hold it tightly against the locking ringassembly. A rubber plug is then inserted into the hole through which theallen set screw has been screwed tightly against the bladder assembly. Asecond allen set screw is then screwed in to squeeze the rubber plugagainst the aft end of the first allen set screw. thereby causing therubber plug to form a tight seal.

The bladder assembly comprises an axially and longitudinally symmetricalbladder and supporting structure. A mushroom shaped bladder anchor isbolted to an anchor bolt and placed head in inside the aft end of thebladder. Each end of the bladder includes a thickened circular axiallysymmetrical lip which defines an opening. Each lip of the bladder thencomes over the underside of the head of the anchor. A disc shaped metalend cap having an axial circular hole of the diam eter of the anchorbolt and shaped to mate with the under portion of the mushroom shapedhead of the anchor is then placed over the anchor and covers the end ofthe bladder. The anchor bolt extends through the axial hole through theend cap and is bolted to a spacer nut, the exterior surface of whichmates with the interior surface of the center guide plug.

The fore end of the bladder assembly utilizes an anchor and anchor bolthaving an axial valve therethrough. This valve extends out of thehousing to permit control in checking of the pressure within thebladder. The anchor bolt is placed through the axial hole in a secondend cap and bolted to a cylindrical plug. The external circumference ofthe plug defines a circumferential groove in which an O ring is placed.When the bladder assembly is placed in the housing, the O ring forms aseal with the interior surface of the housing.

The disc-shaped end caps are welded convex side outward to the screen.The second welding with the bladder and other components inside shouldbe done under water. The interior surface of each end cap is shaped tomate with the bottom of the adjacent anchor. There is metal to metalcontact between the adjacent surfaces of the end cap and anchor and thelip is slightly squeezed between the end cap and anchor to form twoseals, one against the anchor and one against the end cap.

The locking ring assembly comprises three parts which together form anannulus capable of fitting tightly in the groove around the interiorcircumference of the housing. The first two pieces of the assembly areidentical and are inserted first, leaving a space which is filled byputting the third part near the axis and sliding it back against thehousing. A locking ring keeper is inserted to hold the other pieces ofthe assembly against the housing. Each of the first three piecescontains a hole through which the assembly is bolted to the adjacentplug by cap screws. The cap screws overlap the central portion of thelocking ring thereby securely holding the locking ring assembly.

The housing is fabricated from a cylindrical shell of wall thicknesssufficient to stand the anticipated pressures. One end of the shell ismachined to gradually reduce wall thickness as the end is approached.That end is then pressed to reduce the outer surface diameter as the endis approached. Pressing the end so as to reduce the outer diameter has atendency to thicken the walls since the same amount of material thenforms an annu lus of lesser outer diameter. The amount of materialremoved by machining is such that the pressing causes the wall strengthto be constant at the end where the diameter of the cylinder is reducedand equal to the strength of the unmachined and unpressed wall portionsof the cylinder.

The center guide plug interior surface is machined to mate with the aftend of the bladder assembly. A threaded allen set screw hole is tappedthrough it. The center guide plug is then coupled to the narrow end ofthe housing by means such as welding which form a strong permanent seal.Pressing the aft end of the housing through a narrower diameter makes itmate with the aft end of the bladder assembly.

The pulsation dampener according to the present invention has long shelfand use life. The aft end includes a permanent seal around the centerguide plug and a very strong seal by means of the rubber plug betweenthe two allen set screws. The fore end includes a strong seal by meansof the O ring around the plug and the adjacent interior surface of thehousing. The bladder is strongly double sealed at both ends by theanchor squeezing the lip of the bladder against the end cap. Theinterior surface of the end cap, the lip of the bladder and the surfaceof the anchor are designed to form strong seals. The valve extends outthrough the locking ring to permit easy checking and controlling of thepressure inside the bladder. An end plate may be used to cover the foreend of the housing.

The fact that the bladder is longitudinally and axially symmetrical iscritical. Other structures and shapes described herein are examples onlyand may be replaced by various equivalents known to the prior art.

A cover plate is utilized to prevent damage to the loading valve.

DRAWING SUMMARY Reference should be made at this time to the followingdetailed description which should be read in conjunction with thefollowing drawings:

FIG. I is a partially cut away side view of a bladder assembly accordingto the present invention;

FIG. 2 is a side view of a housing for the bladder assembly of FIG. 1',

FIG. 3 is a top view of a four-piece locking ring; and

FIG. 4 is a cross sectional view taken along the lines 4-4 of FIG. 1 ofa selected portion of the bladder assembly of FIG. 1 during pulsation.

DETAILED DESCRIPTION Reference should be made at this time to FIGS. 1, 2and 3 which illustrate a bladder assembly 12 disposed around an axis,and housing 22 ofa pulsation dampener 10. The bladder assembly 12includes a generally cylindrical bladder 14 which is longitudinally andaxially symmetrical, fabricated from a flexible strong material such asartificial rubber, and disposed around an axially symmetrical opening 24at each end which opening 24 is approximately one-half the diameter ofthe bladder 14. The bladder 14 is contained within a generallycylindrical bladder screen 26 having a large quantity of bladder screenholes 28 therethrough. The opening 24 of the aft end of the bladder 14has a bladder anchor I6 with a coaxial anchor bolt 30 threaded therein.The anchor 16 and bolt 30 are co-axial with the bladder 14 and thebladder screen 26. The anchor bolt 30 fits through an axiallysymmetrical hole 46 in an end cap 36 to bolt the anchor 16 to a spacernut 32 which is axially symmetrical and also disposed along the commonaxis. The thickened circular lip 34 which is disposed around the bladderopening 24 is pressed to form a seal with the end cap 36 and a secondseal with the anchor 16. The anchor I6 has a mushroom-like shape. Thedisc shaped end cap 36 has an interior center portion 40 which ispressed to fit tightly over the bottom 42 of the anchor 16 and the lip34. The thickness of each lip 34 is slightly greater than the height ofthe lower portion of the adjacent anchor. There is metal to metalcontact between each anchor and the adjacent end cap 36.

In order to fabricate the bladder assembly 12, the end cap 36 is pressedinto the proper shape, then welded to the cylindrical portion 44 of thescreen 26. The anchor I6 is bolted to the bolt 30 and placed inside thebladder 14. The anchor bolt 30 is oriented outside of the bladder 14through the mating co-axial anchor bolt opening 46 through the end cap36, and bolted to the spacer nut 32.

The fore end of the bladder assembly I2 is built up in a similar mannerwith the following changes. A fore anchor 48 and anchor bolt 51 have anaxial valve therethrough to permit inflation of the bladder 14. The endcap 36 is welded to the cylindrical portion 44 of the screen 26 underwater after the anchors I6, 48 have been inserted in the bladder 14 andthe bladder 14 has been inserted into the cylindrical portion 44 of thescreen 26. The anchor bolt 48 is then bolted to a cylindrical plug 52.The bladder assembly 12 is then inserted in the open end of the housing22 so that the spacer nut 32 nests in and mates with the interior of acenter guide plug 70.

A four-piece locking ring assembly 20 is then inserted as follows. Afirst locking ring segment is laid adjacent the plug 52 and inserted inthe locking ring groove 74 which is a circumferential groove around theinterior of the housing 22. The second locking ring segment 60 is theninserted in the locking ring groove 74 and slid so that one segment end76 is adjacent the segment end 76 of the other segment 60. Accordingly.the second segment ends 78 are parallel and disposed apart the width ofthe locking ring filler 62. The locking ring filler 62 is laid betweenthe second segment ends 78 near the axis of the bladder assembly 12 andslid away from the axis into the groove 74. A Circular locking ringkeeper 58 is then inserted between the other three pieces 60, 62 of thelocking ring assembly 20, thereby stabilizing the locking ring assembly20. A threaded cap screw hole 84 through each of the two locking ringsegments 60 and the locking ring filler 62 continues through the outersurface of the plug 52. The holes 84 are equidistant from each other anddisposed around the axis 120 apart.

An interior allen set screw 64 is then screwed through the threadedallen set screw tapped hole to force the spacer nut 32 toward thelocking ring assembly 20, thereby stabilizing the bladder assembly 12,and

preventing harmful vibrations when pulsations are received. A rubberplug 66 is then pushed up against the interior allen set screw 64 andsqueezed tight forming a seal by the insertion of the outer allen setscrew 68.

Reference should be made at this time to FIG. 4 which illustrates across section along the lines 4 of the bladder 14 during pulsations.Pulsations do not wrinkle the bladder 14, they merely cause it to assumea cloverleaf configuration wherein the total surface area remainsessentially the same. Accordingly, since the surface area of the bladder14 is not folded together or wrinkled during pulsations, the pulsationdampening capability of the pulsation dampener is not reduced andbladder life is extended.

The housing 22 is fabricated from a cylindrical shell of wall thicknesssufficient to stand the anticipated pressure pulsations which act on thebladder assembly through a hole 82 in the housing wall. One end of theshell is machined to gradually reduce wall thickness as the end isapproached. That end is then pressed to reduce the outer surfacediameter as the end is approached. Pressing the end so as to reduce theouter diameter has a tendency to thicken the walls since the same amountof material then forms an annulus of lesser outer diameter. The amountof material removed by machining is such that the pressing causes thewall strength to be constant at the end where the diameter of thecylinder is reduced and equal to the strength of the unmachined andunpressed wall portions of the cylinder.

The center guide plug 70 interior surface is machined to mate with theaft end of the bladder assembly 12. A threaded allen set screw hole 80is tapped through it. The center guide plug 70 is then coupled to thenarrow end of the housing 22 by means such as welding which forms astrong permanent seal. Pressing the aft end of the housing 22 to anarrower diameter reduces weight and provides a closer fit around theaft end of the bladder assembly 12.

A pulsation dampener according to the present invention has long shelfand use life. The aft end includes a permanent seal around the centerguide plug 70 and a rubber plug 66 between the two allen set screws 64,68. The fore end includes a strong seal by means of the O ring 56 aroundthe plug 52 and the adjacent interior surface of the housing 22. Thebladder 14 is strongly double sealed at each end by the anchor 16, 48squeezing the lip 34 of the bladder 14 against the end cap 36. Theinterior surface of the end cap 36, the lip 34 of the bladder 14 and theside of the adjacent anchor 16, 48 are designed to form a strongpermanent seal. The adjacent wall of each end cap 36 and the wall 42 ofeach anchor 16, 48 form a metal to metal contact. The valve 50 extendsout through the locking ring assembly to permit easy checking andcontrolling of the pressure inside the bladder 14. An end plate may beused to cover the fore end of the housing 22.

The fact that the bladder 14 is longitudinally and axially symmetricalis critical. Other structures and shapes described herein are examplesonly and may be replaced by various equivalents known to the prior art.A cover plate is utilized to prevent damage to the loading valve 50.

I claim:

1. A bladder assembly for a pulsation dampener comprising:

a flexible cylindrical bladder with generally dome shaped end walls eachhaving an opening on the axis of the bladder and a thickened annular rimportion surrounding said opening and forming about the opening an inneraxially projecting sealing lip at the inner side of the respective endwall and an outer axially projecting sealing lip at the outer side ofthe respective end wall,

two anchors each having a central portion extending through a respectivebladder opening and an enlarged head portion seating against the innerside of the respective bladder end wall and containing an annularsealing groove receiving the respective inner sealing lip of thebladder,

two anchor bolts each coaxially secured to a respective anchor andextending externally of said bladder,

two generally dome shaped end caps each fitting over a respective end ofsaid bladder and having an annular sealing shoulder surrounding andengaging the respective outer sealing lip of said bladder and a centralopening through which the corresponding anchor bolt extends,

a generally cylindrical screen extending between the two end caps insurrounding relation to said bladder and joined to said end caps, and

one anchor bolt containing an axial passage through which the interiorof said bladder may be pressurized.

2. The bladder assembly according to claim 1 wherein:

each anchor is generally mushroom shaped, and

a nut threaded on each anchor bolt for firmly clamping the respectiveanchor, bladder end wall and sealing lips and end cap together intosealing relamen.

3. A bladder assembly according to claim 2 in combination with:

a generally cylindrical housing containing said bladder assembly andhaving an end wall closing one end of the housing and an opposite openend, and an opening in said housing communicating to the interior ofsaid housing about said bladder,

the nut threaded on said one anchor bolt comprising a disc shaped plugslidably fitting within and sealing said open housing end,

said housing end wall has an inner coaxial recess receiving the othernut, and

means releasably securing said plug in said housing.

4. The combination according to claim 3 including:

a screw threaded in said housing end wall and engaging said other nutfor pressing said bladder assembly tightly against said plug.

5. The combination according to claim 3 wherein:

said housing end wall diminishes in thickness progressively toward saidend wall recess.

6. The combination according to claim 3 wherein:

said plug securing means comprises a locking ring assembly includingseparate parts seating against the outer side of said plug and engagingwithin an internal annular groove in said open housing end, and meansreleasably retaining said parts in said groove.

7. A bladder assembly according to claim 1 wherein:

said bladder end wall openings have equal diameters and said anchorshave the same size and shape.

1. A bladder assembly for a pulsation dampener comprising: a flexiblecylindrical bladder with generally dome shaped end walls each having anopening on the axis of the bladder and a thickened annular rim portionsurrounding said opening and forming about the opening an inner axiallyprojecting sealing lip at the inner side of the respective end wall andan outer axially projecting sealing lip at the outer side of therespective end wall, two anchors each having a central portion extendingthrough a respective bladder opening and an enlarged head portionseating against the inner side of the respective bladder end wall andcontaining an annular sealing groove receiving the respective innersealing lip of the bladder, two anchor bolts each coaxially secured to arespective anchor and extending externally of said bladder, twogenerally dome shaped end caps each fitting over a respective end ofsaid bladder and having an annular sealing shoulder surrounding andengaging the respective outer sealing lip of said bladder and a centralopening through which the corresponding anchor bolt extends, a generallycylindrical screen extending between the two end caps in surroundingrelation to said bladder and joined to said end caps, and one anchorbolt containing an axial passage through which the interior of saidbladder may be pressurized.
 2. The bladder assembly according to claim 1wherein: each anchor is generally mushroom shaped, and a nut threaded oneach anchor bolt for firmly clamping the respective anchor, bladder endwall and sealing lips and end cap together into sealing relation.
 3. ABladder assembly according to claim 2 in combination with: a generallycylindrical housing containing said bladder assembly and having an endwall closing one end of the housing and an opposite open end, and anopening in said housing communicating to the interior of said housingabout said bladder, the nut threaded on said one anchor bolt comprisinga disc shaped plug slidably fitting within and sealing said open housingend, said housing end wall has an inner coaxial recess receiving theother nut, and means releasably securing said plug in said housing. 4.The combination according to claim 3 including: a screw threaded in saidhousing end wall and engaging said other nut for pressing said bladderassembly tightly against said plug.
 5. The combination according toclaim 3 wherein: said housing end wall diminishes in thicknessprogressively toward said end wall recess.
 6. The combination accordingto claim 3 wherein: said plug securing means comprises a locking ringassembly including separate parts seating against the outer side of saidplug and engaging within an internal annular groove in said open housingend, and means releasably retaining said parts in said groove.
 7. Abladder assembly according to claim 1 wherein: said bladder end wallopenings have equal diameters and said anchors have the same size andshape.